Any decent suggestions on Amazon? I freaking hate paying shipping… Also, I’m willing to put more money into a battery if it gives me longer run time. Charger suggestions?
How in the hell are batteries of varying length to the point that they will not work in different things still the same battery?!? Obviously not pissed at you, just the world in general apparently. Any chance on a link to the thread you mentioned, I have no idea how to navigate this website.
ETA: It also kind of pisses me off that there is no information in the description of the light as to which length battery it will take.
ETA2: 68mm is accurate BTW.
Most lights have a battery tube designed to fit up to 70mm batteries, but some newer lights only work with unprotected cell under 67mm. It is often confusing for new users because at first it seems like protected and unprotected measure the same. 18650 is the size of the battery and it stands for 18mm diameter, 65mm long and 0 stands for cylindrical. Of course protected cells are way longer than 65mm however they don’t sell it as 18680/18690. Anyways if you can take good care of your batteries, there is no need to use protected cells at all.
Even with the $2 shipping you will not get a better price on Amazon plus you do not have to worry about sub-standard or fake batteries
In the product description on the amazon page if you look on down they list the cells first as “* Dimensions: 6.8 cm x 1.8 cm x 1.8 cm” then further down they list them as “Product Dimensions 3.1 x 2 x 2 inches” which converts to roughly 78.4mm.
Also there is not an 18650 cell made that will carry over 3500 mAh that I know of so that is warning sign that they are over rated.
Also agree with what bugsy36 said up there….
“Regardless of length……Throw those batteries out!”
And anything you buy from Richard at
http://www.mtnelectronics.com you know will be of good quality and not a fake so it is worth piece of mind even if it cost a couple of dollars extra.
Thanks all. Unfortunately there seems to be a learning curve with everything these days. I bought the recommended batteries and a charger and am returning the Amazon purchase. For reference, those batteries were under 69mm, so might keep that in mind when recommending for other folks.
It is VERY irritating.
I believe XTAR calls their protected batteries 18700 because of this. They are the only company I know that does this.
Got the driver out tonight. This was easy using long-nose pliers with the handles locked open in a drill-press vise.
For those interested in the circuit, it is really simple.
The usual reverse polarity protection diode on the left. From the diode it feeds the MCU on pin 1. The capacitor is for decoupling of the MCU supply voltage. Here it is located after the diode, against BLF wisdom that say it should be before.
The 100k resistor is in parallel with the capacitor. The 30k is across the incoming cell voltage. Not clear, but these probably serve a snubber duty.
The MCU PWM output is on pin 5, which is voltage-divided by the two 15k resistors, before driving the FET gates. In the photo I have bypassed the entry resistor of the divider, marked in green, to drive the FETs with full MCU voltage. Not sure why it was done this way. A 100-220 ohm resistor is more typical in this position. Try at own risk.
I have also moved the black emitter wire to the other side of the 000 pack.
The FETs, prior to modifying the gate drive, had a voltage drop of 130 mV at 4.4 A (30 mohm). The 000 pack had a voltage drop of 32 mV (7 mohm).
After the gate drive modification, the FETs had a voltage drop of 80 mV at 4.5 A (18 mohm).
Voltage drops are the RMS values calculated by an oscilloscope and were also visually confirmed on the ’scope.
Putting everything back together, a fresh 30Q now gives 3.65 A. Before modifications it gave 3.20 A.
Both values are on a cold light (a LED on DD will draw more current as it heats up).
Again, I am not chasing amps. I will upgrade to a FET+1 driver, but for UI reasons (and to get efficient low modes). This was done just out of curiosity.
Finally got mine ordered! I only get paid once a month and I was waiting for the 5a to come available. :party: I’m gearing up to post in the collection thread. 
Nice work DEL and explanation sharpie not that I understood any of it.
Nice work DEL and explanation Sharpie not that I understood any of it.
Interesting. Way back in post 2077 I stated that bypassing the 4 “000” resistors netted the most gain. I had the light doing 5.11A at that point. So I guess y’all worked your way back around to that fact by moving the negative lead to the other side of that bank. The 5.11A was also with a spring bypass in the tail. Changing the FET’s to my Vishay variants really made no difference, although they’re top FET’s hand picked for 15mm and 10mm driver builds. Good that we get to the same place taking different routes.
Wish I knew all the how’s and why’s, would probably have forgotten already anyway even if I did. 
Sharpie, does this mean a bad resistor could be the culprit? Perhaps mislabeled…not really ‘000’?
For info:
My tests were at 4.2 V. I measured 1.9 V drive at the FET gates before the modification.
I did not bother to test with lower voltages.
I did check the diode. It is a Schottky (Vf = 0.25 V).
In post 2048 OscarM posted good quality photos that also show two 15k resistors.
The FETs seems to be Alpha and Omega model AO3400 (or some clone thereof).
Datasheet: http://www.100y.com.tw/pdf_file/ALPHA_AO3400.pdf
From the datasheet:
Interesting graphs:
With the stock driver, we are at Vgs = 2V with a fresh cell.
So if this is indeed our FET, that 1st 15k resistor has to go.
I told myself I was going to leave this driver alone, but, well, you know…
So I broke it open and did the two mods listed above. I moved the negative emitter wire to the other side of the resistor bank, right next to the FETs. I also pulled that first 15k resistor and solder-bridged it. Here’s a crappy cell phone shot of the aftermath:
(The other 15k resistor was straighter that that before I started. Works though, so I left it crooked)
This was a super simple mod to do. Anyone with a soldering iron can do it. My results?
| mod | Amps (tailcap) | candela | Throw |
| Stock | 3.5 | 28,100 | 335 |
| Tailspring replaced/bypassed | ? | 28,700 | 339 |
| Driver mods | 3.9 | 32,300 | 359 |
All testing done with Samsung 30Q cell. I think those are some pretty good performance numbers from such a small light. I really like this one!
It should be pointed out that I think my dmm reads low. I need to build better testing leads. So don’t focus so much on the hard numbers as much as the change. From a stock light, by bypassing the tailspring and doing the two driver mods, I’ve increased my throw by about 7%. Of course heat builds up quite a bit faster than before too. I also poked around on my driver a bit and everything there read like it was supposed to - no mislabeled resistors or anything like was speculated earlier.
To the LAB! 
I put the production driver back in, with the changes I’d already made (bridged bank of sense resistors, new mosfets) and measured it both for current and in the lightbox (simultaneously read)…
4.83A for 1431.75 lumens
Then I pulled it back out, removed that 15K resistor and put an 100 Ohm Vishay resistor in it’s place, re-assembled and tested again with a new cell.
4.86A for 1393.8 lumens
I really don’t see that the recommended change is actually benefiting anything.
Well that’s interesting. Wonder how I can see almost half an amp of gain by bridging those pads and you see almost nothing. Could it be because you swapped your FETs? I don’t claim to understand the electronics theory as well as the rest of you guys, but I’m definitely seeing an increase in performance over here.